It depends on your state laws and whether you have a castle doctrine in effect and also whether the intruder is just attempting to steal or actually intends to kill you. The further you let an aggressor into your house, the more like you are to be injured. Once inside, they also have cover similar or equal to your's. While you are confined to an upstairs bedroom all they have to do is get directly below you on the lower level and fire up through the floor you're standing on. If you feel it's likely the aggessor(s) are going to cause you bodily harm, a more proactive defense would be advisable.